Flip-up sunglasses



FIG. 1 is a front elevational view of flip-up sunglasses showing my new design;

FIG. 2 is a plan view thereof;

FIG. 3 is a right side elevational view thereof, the left side elevational view being a mirror image; and,

FIG. 4 is a rear elevational view thereof. 

The ornamental design for flip-up sunglasses, as shown and described. 